1. Combine first 4 ingredients in a small bowl. Place each chicken breast half between 2 sheets of heavy-duty plastic wrap; flatten to 1/4-inch thickness using a meat mallet or rolling pin. Heat oil in a nonstick skillet coated with cooking spray over medium-high heat. Add chicken, and cook 3 minutes on each side or until done. Remove from pan; keep warm.
2. Add mushrooms to pan; cook 6 minutes or until browned, stirring occasionally. Add Marsala mixture; simmer 4 minutes or until liquid is reduced to about 1/4 cup, scraping pan to loosen browned bits. Spoon over chicken.
carbo rating: 3